Christenings of Martha and Jane Richardson

It has come to light in the last few days that sisters Martha and Jane Richardson married brothers Henry and Joseph Stephenson. Martha married Henry in 1723, and Jane married Joseph in 1726. Interestingly, both Martha and Jane were christened as adults. Martha in 1723 (the year she married) in Hogsthorpe, and Jane in 1725 (the year before she married) in Mumby cum Chapel. There were two other Richardson sisters, Mary and Susannah, but we have found no record of their being christened either as infants or adults.

Was being formally christening a rite that was important in order to be a Stephenson? We are left to speculate.